@@DavidPozEnergy Question for you sir. If you built a 48V pack out of LifePo4 cells than are 280 ah each, how much would that actually store in kWh? I was also wondering if you knew anyone using wind turbines with these type of cells? I want a hybrid system where I am.
Hi Dave Froman. If you are using 280 ah cells, then multiply the ah by the cell nominal voltage. In the case of LiFePO4, that is 3.2v. So: 280 ah times 3.2v = 896 wh (watt hours) per cell. Then multiply that by the number of cells you are using. This video is using 16s. So if you also did a 16s, it would be: 896wh times 16s = 14,336wh or about 14.3kwh.
Next time when you go to drill a hole in the plexiglass, sandwich it between two scrap pieces of 2x4 and drill through the sandwich. You'll have a clean hole in the plexiglass. Hope that helps for the next time :)
OMG, that small blowtorch hands free solder idea has just blown my mind! I have one that I use in the kitchen and living room to light the fire, but I never thought about using it for soldering like that. What a game changer! Brilliant!
Really nice BMS and battery pack, well done for putting this together! For the XT60, 90 connectors, the power source is always female (the protected ones as you say). Most lipos have female XT60s which is a good mental image for reference.
Thanks for another great video! I really appreciate you covering the little details that would cause confusion, such as the counter intuitive BMS wiring order.
@DavidPoz: According to the Tiny BMS Datasheet, the BMS only consumes a few mA, or microA in sleep mode. After connecting the external current sensor and restarting the BMS, it should show the correct current. In general, I think this is a *great* BMS for DIY purposes because you can customize a lot of settings - excellent choice, thanks for sharing. I use one myself too. One problem I noticed on this BMS design: Depending on the characteristics of your inverter, the discharge DC current shown by the BMS may oscillate widely around the "average" DC current. This is especially noticeable at higher currents. Example: 30A average +/- 10A @ 0.1 Hz or so, i.e. a wave period of several seconds or so. If this is the case, then this should not be a problem for the SoC calculation according to Energus. However, this current reading is not very useful for determining the instantaneous average discharge DC current. This oscillation seems to be caused by the interference of the current sensor sampling rate and the frequency at which the inverter "sucks" current pulses from the battery. I wonder if you observe this too.
For anyone reading this: Be sure you get genuine XT60 connectors, not chinese knock-offs, which melts and starts fires. David, this is a quite pretty DIY build. If one does not have a milk crate, MDF or plywood could also do the trick.
When you check the voltage per cell by probing the battery, you gotta be careful. I have shorted it before. As its only one cell it didn't permanently kill the wires or anything but if I left it for any longer there would have been some action
Good video Dave. I think I'll stick to DALYS for now as I just finished up 7 of my batteries and have all the wiring harnesses terminals soldered, for the others, ready to connect. Pretty tedious but good therapy for my Parkinson's disease.
Great video, and great looking tiny BMS with canbus. Seems like a nice install. Love to see it in operation. Note: my buddy's 6 BYD (3 in series 48v) running very well he's so far pushed thru 2500 kw in 4 months, and running 2 AC, one 18k btu and a 12k btu. Many thanks.
Hey David, three things: 1) Powered side is *always* a receptacle/female for safety. Plugs/males represent an exposed shock hazard, so you're doing it correctly. 2) A 3/4" neoprene grommet (t.ly/y6bT) would dress up that hole in the plexi nicely! 3) Since the top of the pack is visible, I'd do a bit of cable management to make things look organized. Also, while not necessary for this project, torching the edges of plexi (MAP or butane) is a quick way to clear the edges.
@@DavidPozEnergy We fabricate vitrines for display cases for galleries, museums, retail and interior spaces all the time. I cut the acylic sheets on the CNC first. External edges are scraped and sanded, then flamed, while internal edges clear when joined using CA glue MAP gas burns hotter than butane/propane, but either works. Be sure to use a pencil point thin clear blue flame. Hold the torch a couple of inches off the edge and perpendicular to it. Like spray painting, start off the edge, sweeping the flame from side to side in one continuous motion, finishing off the opposite edge. Have fun watching the magic happen before your very eyes. It never gets old!
Fun fact on drilling plexi glass, run a twist drill in reverse, or use a very dull bit, and drill with some sort of something on the back side. Basically melt thru it. It’s the best way.
Please add a strain relief for the main poz/neg, and perhaps a way of retaining the relays/contactors..and dont forget as the posts/strips warm and cool, theyll expand and contract...maybe put the isolator in the box as well, and leave the micro port easy to get to..along with an emergency off button or emergency power off port, if you plan on making multiples of this, to link togeather to a single shutoff button...(and or fire system)
While some of us are bored watching the Tiger King and all of the other embarassingly high amp IQ draining boob tube things...... I just got done adding an electric starter to my 10 hp 5000 watt gen..... (but electred to NOT add an on board battery) and then for desert.... I discovered Dr Poz the DIY Guy.... THANKS for contributing to the species ( vs taking away) !!!!! ps.... there are a couple of ok vids showing how to convert an older 10 hp briggs and stratton engine to electric start..... all parts are still available as of Sept 2020.... to avoid buying another battery which would just sit in the gen frame and be used 3 times a year, I elected to add an "Anderson" quick connect to the gen control box which connects to the 12v starter motor solenoid and to engine ground. and then I fabricated a " jumper cable" that has an "anderson" quick connect on one end and ( 12v) Battery connections ( medium amp alligators) on the opposite end ..... now we can start the gen by 1) plug anderson connect to gen receptacle, 2) connect to any car batt.... 3) hit start, 4) disconnect anderson and alligators... =.... electric start but no additional battery to deal with...... p.p.s. I was considering building an adapter mounted to the gen frame, so that I could just connect one of my Ridgid 18v cordless tool batteries. Sure High draw but for only a few seconds.... and my ridgid batteries are covered with the "Lifetime service agreement"... the LSA isnt PERFECT... so it does require "understanding how to use"... and it helps to find a GOOD auth repair shop and AVOID having Home D in that loop.... but THAT would be a sweet mod... pop in the 18 v battery ( whatever battery with a volt limiter) hit start.... take batt out of gen... let cool... place back on charger.
I would like to see a really good video showing normally on and normally off relays and how to control them and how to use them with specific parts links and amp ratings etc . I haven't been able to find any. I know the theory but finding ones that use low energy or the transistor circuits to buy that another comment linked to or are rated high amps etc is hard.
You can get away without the isolator but don't have the battery connected in some way to the laptop (IE powering an inverter with the battery then charging the laptop) while also having the USB connected
Even if inverter is charging the laptop, it will still be fine in this case. This is because all power supplies for laptops that I know of are fully isolated and doesn't share a ground with supply side.
If it can supply 70mA @ 48V that’s 280mA at 12V. Might be enough depending on the step down you use. If you’re going to use another relay you’re going to need a 12V tap off your battery to power the bigger relay. Better off just finding a 48V relay.
I hate to say this, but with the wood you have in the milk crate, you just insulated the entire battery pack and therefore will hold the heat in and therefore the entire pack will have low heat dissipation. That is not good for those cells. What you should have done was make spacers in between each cell and eliminate the plywood sheets. That was the whole pack could breath and therefore eliminate heat between the cells. I have an electrical and electronics engineering background and have a solid working knowledge of batteries and battery construction.
I would really like to buy from you because a manufacturer employee would be tired of doing the same thing over and over again up to a point where he/she may lose it and no longer cares whether something was left lose and here I can see that it is different..
The only thing I would do differently is use Anderson Power Poles instead of the XT60 connectors, since I make heavy use of those for my Ham Radio gear anyway.
The bad thing about using this kind of BMS is that it requires an external contactor and those waste so much energy those coils get HOT and just waste a lot of battery power. I considered one but If MY BMS cant handle the current I need I will just parallel a couple together. seems like the most economical way to go. I can still use a Bluetooth power monitor or a bluetooth active balancer to look at cell voltages.
Depending on how your using these batteries, scooter, bike or solar storage. If solar storage, you could use a shunt trip. The only consumption would be that of a small relay to control the shunt trip breaker, which would be very small.
@@jakeandrules7724 Thanks! that is a great idea. I never heard of a shunt Trip breaker till you just told me. Yes a Shunt Trip breaker and small relay would work great! I googled it and been reading up on them. I really appreciate it.
6:45 Could also just use another one of those XT60 connectors and charge up the bms with a current limited power supply set to the same voltage as the battery instead of the resistor.
Would be nice to find a higher amperage mechanically held contractor that does not require a holding charge to keep contactor closed. I know they make some for lighting circuits but all of the ones I have seen are only good for 30 amps.
I like Anderson Powerpoles rather than XT60. No soldering needed, just a good crimper, and they are genderless - you don't have to worry about male or female, they just go together either way.
It's a shame they don't make higher current versions , or slave units, I'm working on the duybmsv4, i haven't got far yet, I like the direct connection of this , I'd like something similar capable of 300 amps, for my 7s system..
I like it video on that battery but them things are too complex for the average person to use maybe if I watch it you do it enough of times I might be able to do it eventually the lead acid batteries are so much easier
I would like to do something like this to power my 36 Volt EZGO Golf Cart if you have any ideas on how to put it together for at least a 100 AH Battery Pack, Thanks, great videos.
Great video as usual. I came across that bms but when I saw that: Cell balancing: 150 mA, dissipative ...seriously 😑 it will never ever balance a battery pack of 200ish Ah...may be the one you made with brand new prismatic cell will last for a while but as they start aging I wonder how this lil bms will be able to cope.
It's not great but as long as your cells are matched it should be fine. If your cells are getting substantially out of balance where this can't cope, you've got bigger fish to fry.
Great job on the build and explanation! Does the BMS also have linux software or is it only windows? We live in a no-windows household. Only in the outside walls are they allowed ;)
You don't need an USB isolator. There is no point using it in your setup. The only case you would need an isolator is when three things are true: 1) The battery pack is connected to inverter, 2) laptop is charging from that inverter, 3) there is ground path from the laptop power supply. This will never happen with laptop power supply. They are fully isolated already. If you connect it to a desktop it might be slightly different. But using isolator and having one around is a good thing. It is idiotproof.
Thank you. I didn't know what conditions would need an isolator. The manual just said to use an isolator. It didn't say when you didn't need one. I appreciate you helping me out in understanding it.
That looks like a great BMS but those pads where you connect the battery don't seem to be able to handle much current. It would have been better to have studs so you could bolt your battery cables instead of soldering. I would be afraid of the solder melting at high amp draws....!
You are doing a great job, and I love your videos. I'm a newbee, I understand the need for a relay. Can you recommend off-the shelf relays that would be readily accessible to us and show their hookup? Scavenging parts from an electric vehicle is not an option for most of us. Are they that expensive that rather than buy one, you scavenge one and have to buy another for it to function? Also, if you could recommend a proper resistor to use for the hookup would be helpful.
Thanks. Great suggestion. The type of relay I showed (from an EV) can cost more than $200 new. But if you don't need 300 amps, there are more affordable options. Actually, I"m looking at some smaller options for this particular build. But I also want to learn how to use the big relays so I can use it on some bigger batteries. This particular milk-crate build I have 10 gauge wire, and will limit it to 30 amps with a circuit breaker. So all I need is a 30a relay or more. I'm considering using one like this www.mouser.com/ProductDetail/Omron-Automation-and-Safety/MY2-DC48-S?qs=sGAEpiMZZMtGt%252Bn33CgIP%252B2KxmC%252BClteYxZLiC3CNNo%3D
@@DavidPozEnergy What I have in mind is a 48 V system using an MPP 5048 like you had in one of your other videos, and based on Will Prowse's 24 volt hand cart system. I plan on getting a Tesla in the hopefully not too distant future, and hope to use solar to charge it. 30 amps may not be enough to do this. By the way, did your friend get his water pump to work with the MPP 5048?
Yes, the LV5048 worked to start my friends well pump. But he has to be careful not to have a second heavy load on at the same time the pump is trying to start. For example, he had the inverter overload with a microwave and toaster on, and then the pump tried to start. Personally I don't think the LV5048 is ready for prime time. Good luck with your build.
Isn't it OK to tap off 12V from the 4th cell (from the negative terminal)? That gives you a common negative, but a 12V supply for the relay, rather than using another converter. But maybe there's some reason that's not a good idea -- I can't think of one though.
Yes you are correct. These have a max. charging voltage of 3.65 volts per cell. Usually the BMS is set to 3.70v before it will cut power and shut off. It won't cause any damage.
Hi, I am using the same tiny BMS and followed each and every step but when I connect it with USB to UART cable with battery insider installed in my laptop it does not show any thing and it does not detect the BMS. The only thing which I did not follow I have not used the USB isolator and I struggling to find the same isolator which David has used. Any help related to this will be really appreciated. Thank you
Kinda better off with the chinese 2 amp BMS protect and balance unit's. ( I do own one) I would like to see what kind of options it gives you in the software. And they look of better build quality by a smidge than the chinese one's. I would like to see you push this thing with 20-30amps at the bottom and top of voltage range to see how it fairs with these larger brand new cells. My guess (given the two capacitors) is that it charges/discharges the lowest and highest cells one by one till they all get closer and closer together just like the chinese units (very slow process). But perhaps you were only interested in the cell protect and shut off feature of it!? I recently purchased the BYD packs from Battery hook up and a 10 amp zero loss chinese balancer. The balancer will not keep up with these (larger cell) used packs at the bottom and top volt range. Four packs, 16s config. (48v nom.), bottom balanced.. at .5-.10 delta it takes roughly hour in a half to bring them back to .008-.004 with zero current in or out of pack. I wish I knew circuitry, I would love to build a better lager, faster unit to handle large cells.. These units that we find and use are really only good for the one time use bottom balancing for already built packs and smaller cells, think e-bikes.
David, I looked up the Panasonic relay. The coil power rating is 4.2kW (up to 120A and 400Vdc) and the coil voltage is 12Vnom at 353mA. I'm also familiar with the Tiny BMS, and wonder which model you have, low- or high-power. As the low-power model is rated for 30A continuous/60A peak, and you're limiting pack output to 30A with the panel-mount breaker, I'm curious as to why you're choosing to use such a large (and valuable [~$223]) relay to switch external loads. Especially when doing so requires the addition of a buck converter to step battery voltage (48Vdc nominal) down to relay coil voltage (12Vdc), as well as an intermediate relay due to the Panasonic relay's coil current requirement of 353mA outstripping the BMS's external I/O's 250mA continuous rating. If one absolutely needed an external relay, there are better ways to go about it with the Tiny BMS. A contactor, such as Gigavac P125-FDA, has a coil voltage of 48Vdc at just 45mA, well within the Tiny BMS's 250mA rating. This obviates the need for a buck converter and intermediate relay. This $60 contactor switches up to 1,200Vdc at 30A continuous. Lastly, I wanted to point out that this BMS will need to be "woken up" after a low voltage cut-off event when powered by the battery it's protecting. A charge will have to be applied from an external source before a supervised charge will flow via the Tiny BMS.
Hi John, Thanks for your input. I'm learning about the Tiny BMS, and may end up using it on a larger battery in the future. That's why I'm trying to figure out how to use it with a contactor. On a bigger battery I may need to handle a couple hundred amps.
@@DavidPozEnergy I've long suggested that people use relays or contactors, rather than high current BMS units. Besides the high cost, these BMS's generate lots of heat and that concerns me as a single point of failure. Much better, in my opinion, to control external switch gear with the BMS. While I typically design larger systems this way, a recent 26.5kWh system powering equipment requiring high voltage, high current, 3-phase power wouldn't have been possible any other way.
The main terminals can t accidently rotate (cablenis pushed accidently) and hit the terminal of the battery next to it? I rather fold the copper side holding the cable ontop of the side holding the terminal.
the resistor is used to dampen the "in rush" of current into the BMS. Think of it as a restrictor that slows down the amount of juice flowing in. It also can prevent sparks from flying when there is a dramatic difference in voltage potentials. Once the two systems have "equalized", the resistor isn't so important, but it's always a good idea to keep it in the loop. You'll note that the size of that resistor is large, (fat+long with heatsinks) the amount of restriction may be low (low resistance value) but it's ability to handle high current is dictated by it's designed ability to remove that heat. Hope that explains it for you.
Really digging your videos I'm new and learning a bunch. I'm trying to replace my acid batteries from my 5th wheel. What batteries or battery pack would you recommend. I have a 12v inverter but willing to use something else is necessary. Looking for at least 1.5 kilowatt hours..don you think that's overkill?
A battery with a capacity of 1.5kwh might be overkill, or it might be under-sized. I have no idea what your loads are. A 12v inverter might be fine if you want to run a couple light bulbs and a laptop. But anything more than that, like a fridge, induction cook top, washer, dryer, occasional tool, you would be better jumping to 48v. If you know your loads, then see if this online calculator can help you decide: www.altestore.com/store/calculators/off_grid_calculator/
That tiny BMS is doesn’t come with a tiny price! And I don’t like that the BMS uses one cell to power it. You really should have dressed the balance wires, and used kapton tape to hold them in place, so that they stay where you put them.
Wire every 2 cells together in parallel, then series 8 paired groups. This is written as 2p8s, meaning 2 in parallel and 8 in series. If you are on Facebook, then check out the group "DIY Battery" for more help.
That's a question that would depend on what your electrical needs would be. First, find a solar calculator on the internet and calculate how much wattage each item you intend to power uses per hour and then how many hours per day you use it. Then times the days by 31. Take this number and times it by 1.20% and you will be close to the amount of your daily solar power production needs. Check out a sun solar chart to see how many days your location in Jamaica has with or without sun if you are going to need battery power to get you through a few cloudy days and compute the amount of power use per day times average for no sun days to determine your storage needs. If your needs are above 3000 Watts per day or per hour you will need a 48V system. Less than 3K 24V and 1.5K 12V
just started watching and am intrigued by your projects. but i have a lot of questions. i have an RV that i want to build my own battery bank. it is 12 volts. do i just build a 48v pack then step it down for the 12v? how can i make sense of the numbers? jd
12v is OK if you are running 12v lights, 12v radio and little things like that. But the amps will get too heavy if you try to power normal AC loads. So I prefer using 48v for anything that needs an inverter and AC outlets. Sometimes batteries are rated in amp-hours (ah) and if you multiply the ah by the volts you will get the watt-hours (wh). That's a way to normalize comparing a 12v to a 48v. This milk-crate battery is about 3kwh (3,000 wh). If that was in a 12v version it would be 3000/12=250 ah.
Hi David, I have a question about BMS, I have a daly BMS, for lifepo4 8s I found out while charging the battery that the BMS cut off is set to 3.75 this seems a bit high.. can you brig this topic in one of your videos what should be the BMS cut off values? thanks
I agree it seems high, but it's not unusual. Ideally, the charger is set less than that. For example, I use Daly BMS's on my batteries in 16s. 16x3.75=60v My charger is set to 56.8v. If the cells are top balanced then no cell would ever go to 3.75v. The BMS is there is something goes wrong.
@@DavidPozEnergy Yes, exactly, this only happened because the cells are old used cells, they have different resistance, I have balanced them but then on the first cycle there was one cell that was high and the others were low.. the pack voltage was under 29v but this cell was 3.70 :/
OK, sorry I was confused. I need to do a follow up video. It's been powering the house for a couple months, but there still seems to be some glitches in the SOC calculation in the inverter. I want to change out my shunt wires for a shielded twisted pair and see if that helps eliminate some of the deviation. Basically, I'm still fine-tuning it.
I'm still gathering some pieces for my first build (n2.1) and the bms is the next part on the list. It's a simple 12v 4s config. Could I use that bms for my purpose or is there a smaller version with the same functionality? This is going to be an rv battery and being able to connect to a mini pc directly with USB would make monitoring and tweaking the system extremely easy and exactly how I want to do it.
Check out the Electrodacus sbms0. The new version is possibly available September? It has monitoring inbuilt however some users are running Raspberry pi for customized monitoring.
DavidPoz, I have a dumb question that by the way, you are the only person that has a video on the Tiny BMS, I'm using this BMS on a 10s battery pack and looking over the doc file I just thought I would ask you. topmost wire is attached to + (also number 1 cell) and the bottom is connected to - only... thanks
Thanks for checking out the video. I hope to do more videos on this BMS because it seems like it can do a ton of things. You probably already have the manual, but I'll link it just to make sure you are not looking at the quick start guide. manual: file:///D:/Users/David/Downloads/TinyBMS_User_Manual%20(1).pdf On page 14 there is a wiring diagram. I think this one diagram is most useful for understanding the layout. Yes, the top most pin is the main positive of the whole pack. The bottom ones will be left un-used after you finish your 10 cells. 10 cells should mean 11 sense wires. Make sure you check all your wires are correct on the white terminal before plugging into the BMS. If you have just one wire crossed it will (probably) fry the circuit.
@@DavidPozEnergy thanks, I do have the doc file and was looking at page 14 to, but on that page the last wire looks like it goes to - the also looks like it connects to a cell, plus pack + is also + for cell number 1... Just looked weird. I have wired up a bunch of BMS cell 1 + and the last wire goes to - simple
Thanks, everything works great, on page 13 in the doc it talks about a 10s pack and gives you step by step, great documentation! Now I'm waiting for more parts to come to.
You never state how you intend to use your battery builds ie AH and max Amp load. This build looks good for an RV however the Tiny BMS only has a max 30 amp load. What good is a 30 amp BMS for? In my RV i may pull 60 amps running or starting my AC using a Victron Multiplus 3000/24 inverter.
I'm running the loads through an external relay, not through the BMS. So my maximum amps is limited by the relay, or battery, or wire. But not the BMS. The BMS can turn on/off the relay.
@@DavidPozEnergy please mention this in your next video, but I would guess the size of the cables you choose still limits your max amps. I too use a 500 amp contactor to control my 2 Teslas and have it fused at 250 amps using 00 cable. The bms i used SBMS0 exios control all the relays in the chargers and out put devices Multiplus 3000/24.
@@thomasgeriak4322 I've just finished setting up a sbms0 in our caravan using a combination of extios and solid state relays to control all charging and loads and it works fantastically well!
Find local junkyards. Sometimes called "auto recyclers". If you find one locally with an EV (nissan leaf, Chevy Volt, etc) then you can buy the battery from them. I have done that a few times, but I think Battery Hookup is a better deal even with shipping.
Remember the big relay I showed near the end of the video? I pulled that big relay from an EV battery. That is what I will connect to the main positive wire. The current will not pass through the BMS, only through the relay. The BMS can turn the relay on/off.
